qdurham at aol.com (QDurham) wrote:
>>>>I don't know of any adaptations shown by bark. Variation in bark characte=
r=3D
>> is one of god's gifts to botanists.
>>>>Eucalyptus trees show great variation within a locality: gums, boxes,=3D
>> stringybarks, peppermints and iron-barks can all grow close together,=3D
>> though they are different species of course. Conversely, one type of bar=
k=3D
>> can be found in very different environments - again on different species.
>>>>These aren't adaptations?
Not in my book. I think of adaptations as variations that improve the=
fitness of an organism in its environment. I don't see how variations in=
bark are adaptive.
Many biologists believe, like Candide, that everything is for the best in=
the best of all possible worlds. Or, in more biological terms, that every=
stable variant helps to maximise the fitness of the organism in its present=
environment. They justify their beliefs by inventing explanations, not=
always convincing, for each variant.
Some variations are undoubtedly adaptations, but it is not self-evident that=
all of them are. They may have arisen in the past in different=
environments and be no longer adaptive. They may come from genetic drift.
Cheers
Bob Vickery
bob at acsusun.acsu.unsw.edu.auvickery at mpx.com.au